How is electricity generated from Biomass?

Biomass is a type of fuel created from biological materials – wood, plants, manure, and household waste to name a few. In its most basic sense you could count burning wood on a fire as using biomass to generate energy. Biomass can also be used as a low-carbon source of electricity. 

There are multiple ways to generate electricity from biomass, most of which first require the biomass to be prepared. This is achieved by two processes: torrefaction or pyrolysis. Torrefaction is a process that dries out the biomass, producing briquettes and pellets that are easy to transport, resist water absorption, and can’t rot. These briquettes can be burned in a similar way to coal to turn generators and produce electricity. In fact, biomass is often used alongside coal in a process called co-firing, which reduces the need for coal and allows biomass to be used in existing plants, reducing the need for new factories and plants specifically for biomass. 

Pyrolysis also heats the biomass, but without oxygen, which produces several different chemicals. One of them, pyrolysis oil, is a type of tar that can be burned to generate electricity. Another, syngas, can be used as a replacement for natural gas. Another process called gasification can also produce syngas from biomass that can be used to generate electricity. 

In 2017, biomass accounted for nearly 40% of the renewable energy consumed in the UK, and in 2019 it provided 11% of the UK’s electricity overall. It’s important to note that biomass is only considered a renewable energy source if the source of the fuel (for instance, trees or crops) is replenished naturally on a human timescale. It should also be noted that biomass does produce carbon dioxide when burned; however, the emissions from biomass are far lower than those from burning fossil fuels.